Dumbbell



FIG. 1 is a front perspective view of a dumbbell showing my new design;

FIG. 2 is an end view thereof.

FIG. 3 is an opposite end view thereof.

FIG. 4 is a front view thereof

FIG. 5 is a rear view thereof.

FIG. 6 is a top view thereof; and,

FIG. 7 is a bottom view thereof.

The broken lines in the drawings showing the dumbbell illustrate the portions of the dumbbell that form no part of the claimed design. 

CLAIM The ornamental design for a dumbbell, as shown and described. 